The European Union has suspended development aid to Niger and given the authorities there a month to begin talks on a return to "constitutional order", according to EU sources Friday.

- The European Commission, (and the EU nations, have requested consultations with the Niger authorities. - said EU spokesman on development aid John Clancy.

- We hope that these will have a positive outcome for all parties offering a clear roadmap for a return to the constitutional order for Niger - he added.

In the meantime some 458 million euros of European development aid earmarked for Niger up to 2013 - is on hold - he told AFP, while stressing that any humanitarian aid was unaffected.

In a letter was sent to Niger's President Mamadou Tandja on Tuesday by EU Commission chief Jose Manuel Barroso and the Swedish Prime Minister Carl Bildt, whose country holds the rotating EU presidency.

The senior EU leaders called on the Niger authorities to open talks within a month, expressing "deep concern" at the political situation in the west African country and calling for a - return to constitutional order in the shortest possible time - according to the letter seen by AFP in Lagos Friday.

Already, the EU has accused Tandja of "violation of the constitution" by forging ahead on August 4 with a constitutional referendum enabling him to stay in power for three more years, then seek re-election as often as he likes.

Tandja's move was widely opposed in Niger by the trade unions and a number of civil society organisations as well as the political opposition.

The EU warned that it may resort to article 96 of the 2000 Cotonou Accord signed with African, Caribbean and Pacific nations, which deals with the failure to uphold democratic principles and defend human rights.

Article 96 provides for the suspension of EU cooperation with an ACP nation after four months of discussions if the talks lead nowhere.

The EU has already suspended budgetary aid worth 180 million euros (268 million dollars) in protest at the August 4 referendum.

Brussels announced transitional measures against the uranium-rich country pending the outcome of the 120 days of consultations provided for in the Cotonou accord.

On October 20, Tandja's government staged strongly contested parliamentary elections which were boycotted by the opposition. The disputed poll induced the 15-nation Economic Community of West African States (ECOWAS) to suspend Niger's membership for violation of ECOWAS pacts on democracy.